This invention relates generally to railroad cars and, more particularly, to jackets for tank cars and roofs for hopper cars.
Rail car fabrication is a labor intensive process and generally requires numerous weld operations. While at least some welding processes are now automated, e.g., for welding sheets, even automated welding processes require proper set-up of numerous sheets of steel and experienced operators to ensure high quality welds are made by the automated equipment.
Components for rail cars such as tank cars and hopper cars are fabricated by welding steel plates together into a desired configuration. For example, some tank cars require insulation on an outer surface of the tank, and an outer jacket is utilized to contain and protect the insulation. The outer jacket typically is fabricated by welding numerous steel plates together. Although the actual welding is performed by automated machinery, the set-up operations are labor intensive. In addition, experienced welders typically must closely supervise the automated weld process to ensure proper welding.
Similarly, for a hopper car, the hopper car roof is formed by welding a plurality of steel plates together. The sides are then welded to a car cylindrical body, and the roof is located over the sides and welded thereto. Again, the extensive welding required to form the hopper car roof is time consuming and labor intensive.
Methods and systems for fabricating spiral welded cylinders that are particularly well suited for rail car components are described herein. In an exemplary embodiment, a method for fabricating a cylindrical body utilizing a continuous weld includes the steps of feeding a source material including a first edge and a second edge from a coil and straightening at least a portion of the source material. The first edge is offset and the material is fed into a spiral mill so that the material forms a cylinder, or a cylindrical body. The material second edge is positioned adjacent the first edge, and a continuous weld at the interface maintains the material in the formed cylinder. The weld is sometimes referred to herein as a spiral weld because the continuous weld extends along the cylinder in a spiral path.
To fabricate a jacket for a tank car, for example, a longitudinal cut is made in the cylindrical body so that the cut ends can be spread apart. Additionally, a plurality of jackets can be fabricated from a single cylindrical body by making a plurality of longitudinal cuts. The body, or jacket, is then positioned over and secured to the tank. To fabricate a roof for a hopper car, two longitudinal cuts are made to the cylindrical body at select location to provide an arc shaped roof. The roof is then secured to side walls of the hopper car.